PSAT Math : How to find the volume of a cylinder

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #851 : Sat Mathematics

Jessica wishes to fill up a cylinder with water at a rate of  gallons per minute. The volume of the cylinder is  gallons. The hole at the bottom of the cylinder leaks out  gallons per minute. If there are  gallons in the cylinder when Jessica starts filling it, how long does it take to fill?

Possible Answers:

Correct answer:

Explanation:

Jessica needs to fill up  gallons at the effective rate of .  divided by  is equal to . Notice how the units work out.

Example Question #301 : Psat Mathematics

A vase needs to be filled with water.  If the vase is a cylinder that is \dpi{100} \small 12{}'' tall with a \dpi{100} \small 2{}'' radius, how much water is needed to fill the vase?

Possible Answers:

\dpi{100} \small 12\pi

\dpi{100} \small 48\pi

\dpi{100} \small 96\pi

\dpi{100} \small 24\pi

\dpi{100} \small 64\pi

Correct answer:

\dpi{100} \small 48\pi

Explanation:

Cylinder

\dpi{100} \small V = \pi r^{2}h

\dpi{100} \small V = \pi (2)^{2}\times 12

\dpi{100} \small V = 4\times 12\pi

\dpi{100} \small V = 48\pi

Example Question #137 : Solid Geometry

A cylinder has a base diameter of 12 in and is 2 in tall. What is the volume?

Possible Answers:

Correct answer:

Explanation:

The volume of a cylinder is

The diameter is given, so make sure to divide it in half.

The units are inches cubed in this example

Example Question #11 : Cylinders

What is the volume of a cylinder with a radius of 4 and a height of 5?

Possible Answers:

40\pi

54\pi

72\pi

80\pi

60\pi

Correct answer:

80\pi

Explanation:

volume = \pi r^{2}h = \pi \cdot 4^{2} \cdot 5 = 80\pi

Example Question #11 : Cylinders

Claire's cylindrical water bottle is 9 inches tall and has a diameter of 6 inches. How many cubic inches of water will her bottle hold?

Possible Answers:

Correct answer:

Explanation:

The volume is the area of the base times the height. The area of the base is , and the radius here is 3.  

Example Question #140 : Solid Geometry

What is the volume of a circular cylinder whose height is 8 cm and has a diameter of 4 cm?

Possible Answers:

Correct answer:

Explanation:

The volume of a circular cylinder is given by  V = \pi r^{2}h where  is the radius and  is the height.  The diameter is given as 4 cm, so the radius would be 2 cm as the diameter is twice the radius.

Example Question #11 : How To Find The Volume Of A Cylinder

You have tall glass with a radius of 3 inches and height of 6 inches. You have an ice cube tray that makes perfect cubic ice cubes that have 0.5 inch sides. You put three ice cubes in your glass. How much volume do you have left for soda? The conversion factor is 1\hspace{1 mm}inch^3=0.0163871\hspace{1 mm}L.

Possible Answers:

2.77\hspace{1 mm}L

54\pi\hspace{1 mm}inches^3

1.69\hspace{1 mm}L

169.27\hspace{1 mm}mL

\frac{3}{8}inches^3

Correct answer:

2.77\hspace{1 mm}L

Explanation:

First we will calculate the volume of the glass. The volume of a cylinder is

V=\pi r^2 h

V=\pi (3\hspace{1 mm}inches)^2 \times 6\hspace{1 mm}inches = 54\pi\hspace{1 mm}inches^3

Now we will calculate the volume of one ice cube:

V=lwh=l^3=(\frac{1}{2}\hspace{1 mm}inch)^3=\frac{1}{8}\hspace{1 mm}inches^3

The volume of three ice cubes is \frac{3}{8}\hspace{1 mm}inches^3. We will then subtract the volume taken up by ice from the total volume:

54\pi\hspace{1 mm}inches^3-\frac{1}{8}\hspace{1 mm}inches^3\approx 169.27\hspace{1 mm}inches^3

Now we will use our conversion factor:

169.27\hspace{1 mm}inches^3\times \frac{0.016387\hspace{1 mm}L}{1\hspace{1 mm}inch^3}=2.77\hspace{1 mm}L

Example Question #10 : Cylinders

A water glass has the shape of a right cylinder. The glass has an interior radius of 2 inches, and a height of 6 inches. The glass is 75% full. What is the volume of the water in the glass (in cubic inches)?

Possible Answers:

Correct answer:

Explanation:

The volume of a right cylinder with radius  and height  is:

 

Since the glass is only 75% full, only 75% of the interior volume of the glass is occupied by water. Therefore the volume of the water is:

Example Question #1 : How To Find The Volume Of A Cylinder

A circle has a circumference of 4\pi and it is used as the base of a cylinder. The cylinder has a surface area of 16\pi. Find the volume of the cylinder.

Possible Answers:

10\pi

2\pi

8\pi

6\pi

4\pi

Correct answer:

8\pi

Explanation:

Using the circumference, we can find the radius of the circle. The equation for the circumference is 2\pi r; therefore, the radius is 2.

Now we can find the area of the circle using \pi r^{2}. The area is 4\pi.

Finally, the surface area consists of the area of two circles and the area of the mid-section of the cylinder: 2\cdot 4\pi +4\pi h=16\pi, where h is the height of the cylinder.

Thus, h=2 and the volume of the cylinder is 4\pi h=4\pi \cdot 2=8\pi.

Example Question #11 : How To Find The Volume Of A Cylinder

A metal cylindrical brick has a height of . The area of the top is .  A circular hole with a radius of  is centered and drilled half-way down the brick. What is the volume of the resulting shape?

Possible Answers:

Correct answer:

Explanation:

To find the final volume, we will need to subtract the volume of the hole from the total initial volume of the cylinder.

The volume of a cylinder is given by the product of the base area times the height: .

Find the initial volume using the given base area and height.

Next, find the volume of the hole that was drilled. The base area of this cylinder can be calculated from the radius of the hole. Remember that the height of the hole is only half the height of the block.

Finally, subtract the volume of the hole from the total initial volume.

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